Re: [PATCH 2/2] drm/amdgpu: stop disabling irqs when it isn't neccessary

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Jun 13, 2016 at 04:12:43PM +0200, Christian König wrote:
> From: Christian König <christian.koenig@amd.com>
> 
> A regular spin_lock/unlock should do here as well.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>

Just drive-by comment, but you can't mix up irq spinlocks with normal
ones. And there's places where this is still irqsave, but some of these
functions can be called directly from the scheduler kthread. You can only
drop the _irqsave if you know you're always called from hardirq context
(softirq isn't enough), or when you know someone already disabled
interrupts. And you can simplify the _irqsave to just _irq when you are in
always in process context and irqs are always still enabled.

On a super-quick look seems fishy.
-Daniel

> ---
>  drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
> index b1d49c5..e13b140 100644
> --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
> +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
> @@ -331,17 +331,16 @@ static void amd_sched_job_finish(struct work_struct *work)
>  	struct amd_sched_job *s_job = container_of(work, struct amd_sched_job,
>  						   finish_work);
>  	struct amd_gpu_scheduler *sched = s_job->sched;
> -	unsigned long flags;
>  
>  	/* remove job from ring_mirror_list */
> -	spin_lock_irqsave(&sched->job_list_lock, flags);
> +	spin_lock(&sched->job_list_lock);
>  	list_del_init(&s_job->node);
>  	if (sched->timeout != MAX_SCHEDULE_TIMEOUT) {
>  		struct amd_sched_job *next;
>  
> -		spin_unlock_irqrestore(&sched->job_list_lock, flags);
> +		spin_unlock(&sched->job_list_lock);
>  		cancel_delayed_work_sync(&s_job->work_tdr);
> -		spin_lock_irqsave(&sched->job_list_lock, flags);
> +		spin_lock(&sched->job_list_lock);
>  
>  		/* queue TDR for next job */
>  		next = list_first_entry_or_null(&sched->ring_mirror_list,
> @@ -350,7 +349,7 @@ static void amd_sched_job_finish(struct work_struct *work)
>  		if (next)
>  			schedule_delayed_work(&next->work_tdr, sched->timeout);
>  	}
> -	spin_unlock_irqrestore(&sched->job_list_lock, flags);
> +	spin_unlock(&sched->job_list_lock);
>  	sched->ops->free_job(s_job);
>  }
>  
> @@ -364,15 +363,14 @@ static void amd_sched_job_finish_cb(struct fence *f, struct fence_cb *cb)
>  static void amd_sched_job_begin(struct amd_sched_job *s_job)
>  {
>  	struct amd_gpu_scheduler *sched = s_job->sched;
> -	unsigned long flags;
>  
> -	spin_lock_irqsave(&sched->job_list_lock, flags);
> +	spin_lock(&sched->job_list_lock);
>  	list_add_tail(&s_job->node, &sched->ring_mirror_list);
>  	if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
>  	    list_first_entry_or_null(&sched->ring_mirror_list,
>  				     struct amd_sched_job, node) == s_job)
>  		schedule_delayed_work(&s_job->work_tdr, sched->timeout);
> -	spin_unlock_irqrestore(&sched->job_list_lock, flags);
> +	spin_unlock(&sched->job_list_lock);
>  }
>  
>  static void amd_sched_job_timedout(struct work_struct *work)
> -- 
> 2.5.0
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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